This invention relates to an improved screw cap assembly. More specifically, it relates to such a screw cap assembly, especially adapted for closing the liquid supply inlet of an automotive gasoline or lubricating oil reservoir tank and the like.
As is well known, such an assembly comprises a manually operable and rotatable handle piece; a hollow screw plug proper in the form of a peripherally screw-threaded sleeve which is normally mechanically connected with said handle piece for jointly turning togetherwith; and a cylinder lock mounted in the said screw plug proper for being locked or unlocked from outside with a manual key normally common to the conventional automotive engine key. When the cylinder lock is operated to its locking position, the handle piece is freed from its mechanical connection with the screw plug proper, thus the former is brought into a freely and independently turnable position. On the other hand, when the cylinder lock is key-manipulated from outside to its unlock position, the mechanical connection of the handle piece with the screw cap proper is restored so that both members are rotatable together.
The purpose of the above free-connection is to prevent forced and intentional breakage of the screw cap assembly by an unauthorized person, which may occur if the handle piece and the screw cap proper are mechanically connected with each other in a rigid and permanent way.
When gasoline or the like liquid is supplemented to the tank reservoir through its supply inlet, the cylinder lock must be unlocked at first and then the cap screw assembly is unscrewed. After finishing of the fuel or the like supplementing job, the screw cap assembly is reintroduced into the tank inlet and screwed thereinto. And then, the cylinder lock is brought into its locked position by use of the key, for freeing the handle piece from rigid connection with the cap screw proper. With such conventional design of the screw cap assembly, the lock operation thereof must be made only after tight screwing of the screw cap and for this job, the key is necessary for use by the gasoline stand service man for the locking job and thus, the car driver can not enjoy car radio programs or the like so far as the key is held by the service man. In addition, the car gasoline gauge can not operate without the key held in position on the car instrument panel.
It is, therefore, the first object of the invention to provide an improved screw cap assembly of the above kind in which the handle piece can be made free in its unscrewing direction, but is coupled to the screw plug in its tank inlet-closing direction, even if the cylinder lock has been locked.
It is a further object of the invention to provide an improved screw cap assembly which is provided with such means for preventing excess tightening of the screw cap.
It is still a further object to provide an improved screw cap assembly having such manually operable handle piece capable of separating from connection with the screw cap proper when a sudden and severe mechanical shock is applied to the assembly.